Overview of sensors channels and frequencies
If many acoustic systems are used simultaneously, due care must be taken to prevent acoustic interference between the different instruments. In order to avoid interferences between sensors, their communication channel must be different. If you have two or more gear monitoring sensors on board, you need to make sure they do not use the same frequency range.
All sensors are provided by Kongsberg Discovery with predefined communication channels.
Note
It may be required to change one or more communication channels, and there may be many reasons for this.
•  You have more than one of each sensor. For example, if you have three temperature sensors, they MUST communicate on three different channels.
•  Other vessels near yours use the same gear monitoring system (or similar) and they have one or more of their sensors set up to the same communication channels as you have. This will create interference as you will “read” other sensors.
•  If your sensors are set up to use communication channels too close to each other (for example, if you have chosen channels 4, 5 and 6), this will limit the speed of the vessel. The reason for this is the Doppler effect.
•  If you operate at the maximum range of the sensors, you may be able to increase this range slightly if you use lower communication channels. This is because the lower communication channels use lower transmission frequencies.
Our gear monitoring sensors communicate on a frequency range from 40 to 50 kHz. The following table shows the equivalence of communication channels to frequencies of different gear monitoring sensors
Frequencies
(kHz)
PX TrawlEye
Channel
PX MultiSensor Mk2
Channel
PX MultiCatch
Channel
PX Universal
Channel
PX Flow
Channel
PI Sensors
Channel
39.4 - 40.7 1 1L 1L 1L 1L Not used
1H 1H 1H 1H
40.8 - 42.1 2 2L 2L 2L 2L Not used
2H 2H 2H 2H
42.2 - 43.5 3 3L 3L 3L 3L Not used
3H 3H 3H 3H
43.6 - 44.9 4 4L 4L 4L 4L 1 – 30
4H 4H 4H 4H
45.0 - 46.3 5 5L 5L 5L 5L
5H 5H 5H 5H
46.4 - 47.7 6 6L 6L 6L 6L
6H 6H 6H 6H
47.8 - 49.1 7 7L 7L 7L 7L
7H 7H 7H 7H
49.2 - 50.5 8 8L 8L 8L 8L
8H 8H 8H 8H Not used
Make sure you do not have any interfering channel if you have a PI Receiver working simultaneously with an SR15 or SR70 Receiver.
Simrad PxPos and ITI sensors frequencies
Sensor type
Interrogation frequency [Hz] Reply frequency 1 [Hz] Reply frequency 2 [Hz] Reply frequency 3 [Hz]
Depth 27489 27306 27675
Depth / Temperature / Remote 1 & 2 27489 27306 27675 27306
Height 1 30340 30117 30567 30117
Height 2 31030 30796 31267 30796
Spread 1 31751 31507 32000
Spread 2 32251 31507 32000
SR15 and SR70 Receiver Units
•  Frequency range: 39.4 to 50.5 kHz.
•  An SR type receiver has 8 communication channels when interfacing the following sensor/sensors:
–  PX TrawlEye
•  An SR type receiver has 16 communication channels (1 Low to 8 High) when interfacing the following sensor/sensors:
–  PX MultiSensor Mk2
–  PX MultiCatch
–  PX Universal
–  PX Flow
PI50 and PI60 Receiver Units
•  The PI50/PI60 Receiver Units frequency range is from 43.6 to 49.4 kHz. It works in the same operational frequency band as PX TrawlEye sensor channels 4 to 8 and the rest of PX sensors channels 4L to 8H.
•  The PI50/PI60 Receiver Units channels are 1 to 30.
Lower frequencies are better for long range communications. If you need long-range communication, you should use low channels.